Prosthetic ankle and method of controlling same based on adaptation to speed

ABSTRACT

Prosthetic devices and methods of controlling the same are provided. A prosthetic ankle device includes a foot unit and lower limb member moveable relative to one another and defining an ankle angle therebetween. The prosthetic ankle device further includes a controller to operate the device using different ankle angles depending on, for example, a user&#39;s gait speed. Methods of controlling the prosthetic ankle device include operating the device at different ankle angles depending on gait speed. For example, the prosthetic ankle device can provide for relatively more dorsiflexion at relatively slower gait speeds and relatively more plantarflexion at relatively faster gait speeds.

INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS

Any and all applications for which a foreign or domestic priority claim is identified in the Application Data Sheet as filed with the present application are hereby incorporated by reference under 37 CFR 1.57. This application is a continuation of U.S. application Ser. No. 14/206,956, filed Mar. 12, 2014, which claims priority benefit of U.S. Provisional Application No. 61/785,248, filed Mar. 14, 2013, the entirety of each of which is hereby incorporated by reference herein and should be considered a part of this specification.

BACKGROUND Field

The present disclosure relates to prosthetic devices including control systems and methods for controlling prosthetic devices.

Description of the Related Art

Various types of prosthetic devices are available as artificial substitutes for a missing body part, such as an arm or leg. Prosthetic joints are also available as substitutes for human joints, such as an ankle or knee. Electronically controlled prosthetic devices, or “mechatronic” devices, can provide safer and more natural movement. Improvements to control systems for such mechatronic devices could advantageously allow the devices to more closely approximate the movement of natural joints and provide users with a greater range of motion and greater stability.

SUMMARY

The present disclosure provides prosthetic devices and methods for controlling prosthetic devices, for example, prosthetic joints. The methods described herein can be used to control prosthetic devices of various types and structures. For example, the methods can be used to control actuated joints that are active or passive. The methods described herein can also be used to control prosthetic devices operatively coupled to and used by both transfemoral and transtibial amputee users.

Some embodiments of the present disclosure provide methods of controlling a prosthetic ankle device that includes a foot unit and a lower limb member configured to move relative to the foot unit and defines an angle between the foot unit and lower limb member. In one embodiment, a method of controlling the prosthetic ankle device includes operating the prosthetic ankle device using a neutral ankle angle at a gait speed less than a first threshold speed. The method further includes operating the prosthetic ankle device using a speed adaptive ankle angle at a gait speed at or above the first threshold speed and below a second threshold speed. The speed adaptive ankle angle is less than the neutral ankle angle so that the prosthetic ankle device is relatively more dorsiflexed than when the prosthetic ankle device is operating using the neutral ankle angle. At a gait speed at or above the second threshold speed, the method includes operating the prosthetic ankle device using a speed adaptive ankle angle that is more than the neutral ankle angle. The prosthetic ankle device is therefore relatively more plantarflexed than when the prosthetic ankle device is operating using the neutral ankle angle.

In some embodiments, at a gait speed at or above the first threshold speed, the speed adaptive ankle angle increases as the gait speed increases. The speed adaptive ankle angle used to operate the prosthetic device can also increase as the gait speed increases at or above the second threshold speed. In some embodiments, at or above a third threshold speed, the speed adaptive ankle angle remains constant as gait speed increases.

In some embodiments of the present disclosure, a prosthetic system includes a prosthetic ankle device and a controller. The prosthetic ankle device includes a foot unit and a lower limb member configured to move relative to the foot unit and defines an angle between the foot unit and lower limb member. The controller is configured to operate the prosthetic ankle device using a neutral ankle angle at a gait speed less than a first threshold speed. At a gait speed at or above the first threshold speed and below a second threshold speed, the controller is configured to operate the prosthetic ankle device using a speed adaptive ankle angle that is less than the neutral ankle angle so that the prosthetic ankle device is relatively more dorsiflexed than when the prosthetic ankle device is operating using the neutral ankle angle. At a gait speed at or above the second threshold speed, the controller is configured to operate the prosthetic ankle device using a speed adaptive ankle angle that is more than the neutral ankle angle so that the prosthetic ankle device is relatively more plantarflexed than when the prosthetic ankle device is operating using the neutral ankle angle.

All of these embodiments are intended to be within the scope of the disclosure herein. These and other embodiments will become readily apparent to those skilled in the art from the following detailed description having reference to the attached figures, the disclosure not being limited to any particular disclosed embodiment(s).

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the present disclosure are described with reference to the drawings of certain embodiments, which are intended to schematically illustrate certain embodiments and not to limit the disclosure.

FIG. 1A illustrates a perspective view of an example embodiment of a prosthetic ankle device;

FIG. 1B illustrates a side view of the prosthetic ankle device of FIG. 1A;

FIG. 1C illustrates a cross-sectional view of the prosthetic ankle device of FIGS. 1A and 1B;

FIG. 2 illustrates a perspective view of an example embodiment of a transfemoral prosthetic device including the prosthetic ankle device of FIGS. 1A-1C and an example embodiment of a prosthetic knee device;

FIGS. 3 and 4 illustrate example embodiments of prosthetic knee devices;

FIG. 5 illustrates a block diagram of an example embodiment of a control system for a prosthetic device;

FIG. 6 illustrates a graph depicting the range of ankle motion of an example embodiment of a prosthetic ankle device during one full stride on a level surface;

FIG. 7 illustrates a graph of the difference between a speed adaptive ankle angle and a neutral ankle angle at various gait speeds for an example embodiment of a control system for a prosthetic ankle device;

FIG. 8 illustrates a graph depicting the range of ankle motion of an example embodiment of a prosthetic ankle device during one full stride on a level surface at a relatively slower gait speed; and

FIG. 9 illustrates a graph depicting the range of ankle motion of an example embodiment of a prosthetic ankle device during one full stride on a level surface at a relatively faster gait speed.

DETAILED DESCRIPTION

Although certain embodiments and examples are described below, those of skill in the art will appreciate that the disclosure extends beyond the specifically disclosed embodiments and/or uses and obvious modifications and equivalents thereof. Thus, it is intended that the scope of the disclosure herein disclosed should not be limited by any particular embodiments described below.

With reference to FIGS. 1A-1C, an example embodiment of a prosthetic ankle device 100 can include an attachment member, in the form of a lower limb member 102, operatively coupled to a foot unit 104. As used herein, the term “attachment member” is a broad term and is used in its ordinary sense and in a prosthetic foot embodiment relates to, without limitation, any member that attaches either directly or indirectly to the foot unit 104 and is moveable in relation thereto, for example by a pivoting motion, and is used to attach the prosthesis 100 to a stump or intermediate prosthesis. As illustrated, the attachment member may take the form of a lower limb member. In other embodiments, for example an orthotic embodiment, the attachment member may be used to attach to and support a body part, such as with a brace, which also is moveably connected to a second member, such as a foot unit, which would also attach to and support a body part, such as the foot. In one embodiment, the lower limb member 102 is a generally elongated member with a main longitudinal axis that extends in about a tibial direction, that is, a direction that extends generally along the axis of a natural tibia bone. For example, FIGS. 1A and 1B depict the lower limb member 102 as having a generally vertical orientation.

The illustrated lower limb member 102 includes an attachment portion 108. The attachment portion 108 can couple the lower limb member 102 to a pylon or to another prosthetic device, as described below. In other embodiments, the attachment portion 108 can couple the lower limb member to the user's residual limb, e.g., to a socket coupled to the residual limb. In some embodiments, no attachment portion 108 may be provided at all, such as when the lower limb member is directly integrated with a prosthetic knee. The lower limb member 102 can be movably, e.g., pivotally, attached to the foot unit 104 to form a pivoting ankle joint. The prosthetic ankle device 100 can therefore provide for heel height adjustability. In some embodiments, a prosthetist or user can determine or calibrate a neutral ankle angle for the prosthetic device 100. The neutral ankle angle can be an angle between the foot unit 104 and lower limb member 102 that is suited for the particular user when standing still on level ground.

The foot unit 104 can include various types of prosthetic or orthotic feet. In some embodiments, the foot unit 104 includes a foot or upper plate and/or a heel or lower plate extending between a heel portion 104 a of the foot 104 and a toe portion 104 b of the foot 104. In some embodiments, the foot unit 104 can include such features as shock absorption and/or a split toe configuration, which can facilitate movement on uneven terrain. The foot unit 104 can further include a foot cover or cosmesis.

In the illustrated embodiment, the lower limb member 102 includes a cover 106 that houses and/or protects the inner components of the lower limb member 102. In some embodiments, the lower limb member 102 also includes a rear cover 106 b. In some embodiments, the cover 106 can be rounded or shaped in the form of a natural human leg. In the illustrated embodiment, a lower end of the lower limb member 102 is coupled to the foot unit 104 at a pivot assembly 114. The pivot assembly 114 allows for angular movement of the foot unit 104 with respect to the lower limb member 102. For example, in one embodiment, the pivot assembly 114 comprises at least one pivot pin. In other embodiments, the pivot assembly 114 comprises a hinge, a multi-axial configuration, a polycentric configuration, combinations of the same or the like. In some embodiments, the pivot assembly 114 is located on a portion of the foot unit 104 that is near a natural ankle location of the foot unit 104. The pivot assembly 114 can be bolted or releasably connected to the foot unit 104.

In some embodiments, the prosthesis 100 includes an actuator 116 that controls, adjusts, or otherwise affects the ankle angle, or angle between the foot unit 104 and the lower limb member 102. The actuator 116 can be active or passive. In the illustrated embodiment, a lower end of the actuator 116 is coupled to the foot unit 104 at a first attachment point 118, and an upper end of the actuator 116 is coupled to the lower limb member 102 at a second attachment point 120. Linear motion (or extension and contraction) of the actuator 116 actively adjusts the ankle angle between the foot unit 104 and the lower limb member 102. The actuator 116 can includes, for example, a double-screw motor, single-screw motor, piston cylinder-type structure, servomotor, stepper motor, rotary motor, spring, fluid actuator, or the like. In other embodiments, the actuator 116 comprises a passive actuator, for example a hydraulic or pneumatic actuator. The actuator can provide damping to control or affect the ankle angle. Additional details regarding prosthetic ankle devices and actuators, among other details that may be combined, added or interchanged with details described herein, can be found in U.S. Pat. Nos. 7,431,737; 7,896,927; and 7,637,959, the entirety of each of which is hereby incorporated by reference herein, and in U.S. Pat. No. 8,057,550, a copy of which is included herein as Appendix A and the entirety of which is hereby incorporated by reference herein.

Whereas a trans-tibial amputee may only need a prosthetic ankle device, a transfemoral amputee may also need a prosthetic knee joint. Various types of prosthetic knees, including mechanical knees and active or passive actuated knees, can be used in combination with the prosthetic ankle device 100. For example, FIG. 2 illustrates a transfemoral prosthetic device 200 including the prosthetic ankle device 100 in combination with an example embodiment of a prosthetic knee device 250. Other example prosthetic knees are shown in FIGS. 3 and 4. Various prosthetic knees, and other features that may be combined, added or interchanged with details described herein, are described in U.S. Pat. Nos. 5,314,498; RE42,903; and 7,736,394, and U.S. Patent Publication No. 2009/0299480, the entireties of which are hereby incorporated by reference herein. It will be appreciated that although some embodiments of a prosthetic device encompassed by this disclosure may include discrete a prosthetic ankle device and a discrete prosthetic knee device coupled together, as shown in FIG. 2, other embodiments of the prosthetic device may have both a prosthetic ankle portion and a prosthetic knee portion integrated together and forming a single prosthesis.

The prosthetic ankle device 100 can include a control system 300 to control operation of the actuator 116, for example as shown in the block diagram of FIG. 5. In some embodiments, the prosthetic ankle 100 and a knee used in combination with the ankle 100 can be controlled by a single control system 300. The control system 300 can include any or all of: at least one sensor module 302; the prosthetic ankle device 100; a central processing unit (“CPU”) or controller 305; a memory 306; an interface module 308; a control drive module 310; actuator 116; and a power module 318. The control system 300 can process data received from the sensor module 302 with the CPU 305. The CPU 305 communicates with the control drive module 310 to control operation of the actuator 116. The CPU 305 can also receive commands from a user and/or other device through the interface module 308.

In some embodiments, the sensor module 302 of the control system 300 can be used to measure one or more variables relating to the prosthetic ankle device 100. The sensor module 302 can include one or more sensors of various types located on the prosthetic ankle device 100 or elsewhere, for example, the user's sound limb or residual limb. For example, the sensor module 302 can include one or more accelerometers, for example, three accelerometers to measure acceleration of the prosthetic ankle device 100 in three substantially mutually perpendicular axes. Additionally or alternatively, the sensor module 302 can include, for example, one or more gyroscopes configured to measure angular speed, plantar pressure sensors configured to measure plantar pressure of the foot unit 104, kinematic sensors, load sensors, flex sensors, myoelectric sensors, and/or other sensors as desired or required.

The sensors can be used to measure one or more variables and/or obtain information relating to, for example, one or more of: the position of the prosthetic ankle device 100 with respect to the ground; the inclination angle of the prosthetic ankle device 100; the direction of gravity with respect to the prosthetic ankle device 100; and the like. In some embodiments, the sensors can be used to measure one or more variables relating to or indicative of the gait cycle of the user, for example to detect or determine heel strike, mid stance, late stance, toe off, and/or swing. The one or more sensors can also or alternatively be used to measure one or more variables indicative of various gait patterns and/or events. For example, one or more sensors can measure one or more variables used to detect or determine when the user is in a standing or stopped position, walking on level ground, walking on inclines and/or declines, ascending and/or descending stairs, sitting, or the like. In some embodiments, one or more sensors are capable of directly measuring or detecting a particular position, movement, state, condition, or the like of the prosthetic ankle device 100. In some embodiments, one or more sensors measure one or more variables relating to or indicative of a particular position, movement, state, condition, or the like and provide data to the controller 305, which can process the data to calculate or determine the position, movement, state, condition, or the like.

In some embodiments, the sensor module 302 can be used to measure one or more variables indicative of the user's relative or absolute gait speed. In some embodiments, the sensor module 302 includes one or more sensors that directly measure or determine absolute speed in units of distance per time, e.g., meters/second. Examples of such sensors are available from Dynastream Innovations, Inc. In some embodiments, the controller 305 calculates or determines relative or absolute gait speed using data provided by one or more sensors. For example, the controller 305 may receive from one or more sensors or calculate or determine the duration of the stance phase of the gait cycle and/or the cadence of the user's gait (strides per unit of time). The controller 305 can compare these values to experimental data (for example the particular user's normal stance duration or cadence as determined, measured, and/or recorded during a training or set-up session), a look-up table, or the like to determine whether the user is walking relatively slowly, relatively fast, or at a normal speed or pace. For example, if the stance phase is shorter than the user's normal stance phase, the controller 305 can determine that the user is walking relatively fast.

The prosthetic ankle device 100 can be configured to adjust for various stages of the user's gait cycle, as well as various gait patterns or events, for example, walking on level ground, walking on inclines or declines, or ascending or descending stairs, etc. FIG. 6 illustrates a graph depicting a possible range of motion of an embodiment of the prosthetic ankle device 100 during one full stride on a level surface. As shown, the x-axis represents various points during one full stride of a user (i.e., 0 to 100 percent of the stride). The y-axis represents the ankle angle of the prosthetic ankle device 100 relative to the neutral ankle angle. During one full stride, the ankle angle can vary from about 20° plantarflexion (i.e., neutral ankle angle+20°) to about 10° dorsiflexion (i.e., neutral ankle angle −10°). In some embodiments, the prosthetic ankle device 100 can be configured to provide for toe lift, or relative dorsiflexion, during a swing phase of the gait cycle. This can advantageously provide for toe clearance during swing so that the toe does not catch on the walking surface and cause the user to stumble. The prosthetic ankle device 100 can be configured to adjust for walking on inclines or declines by decreasing or increasing the ankle angle, respectively, to an adjusted ankle angle. In some embodiments, the prosthetic ankle device 100 remains locked at the adjusted ankle angle over the course of the gait cycle. In some embodiments, the prosthetic ankle device 100 is configured to adjust or allow adjustments for various stages of the user's gait cycle and/or gait patterns or events using or based on the adjusted ankle angle. Additional details on adjusting for inclines, declines, stages of the gait cycle, and/or gait patterns and events can be found in U.S. Pat. No. 7,637,959, which has been incorporated by reference herein.

In some embodiments, the prosthetic ankle device 100 can be configured to adapt to different gait speeds of the user. For example, the prosthetic ankle device 100 can provide for relatively more dorsiflexion at relatively slower gait speeds and relatively more plantarflexion at relatively faster gait speeds. Providing relatively more dorsiflexion can inhibit or reduce heel rise during mid to late stance, which can cause a shortened stride and reduced plantarflexion or push-off at toe off, as is more common at slower gait speeds in healthy individuals. Providing relatively more plantarflexion can conversely provide increased plantarflexion or push-off at toe off and a lengthened stride, as is more common at faster gait speeds in healthy individuals.

The controller 305 can be configured to operate the prosthetic ankle device 100 using different ankle angles depending on the user's gait speed, for example, depending on whether the user's gait speed is below, at, or above certain threshold speeds or whether the user is walking relatively slowly or relatively fast. As used herein, the terms “operate” and “operating” are broad terms and include, without limitation, adjusting, moving, controlling, functioning, causing to function or behave in a particular manner, effecting a particular state or condition, and/or providing in a particular state or condition. For example, the controller 305 can be considered to be operating the prosthetic ankle device 100 anytime a user is wearing the device, regardless of whether the user is moving or whether the ankle angle is changing. In some embodiments, the controller 305 operates the prosthetic ankle device 100 using or based on the neutral ankle angle when the user's gait speed is below a first threshold. At or above the first threshold speed, the controller 305 operates the prosthetic ankle device 100 using a speed adaptive ankle angle. As used herein, the term “speed adaptive ankle angle” is a broad term and can refer to, for example, an initial angle at which a prosthetic ankle device operates at a given speed, and can be an angle at which the prosthetic ankle device is locked over a gait cycle or a baseline angle from which the prosthetic ankle device makes or allows adjustments over a gait cycle or in response to certain conditions.

In some embodiments, when the gait speed is between the first threshold speed and a second threshold speed, inclusive of the first threshold speed, the speed adaptive ankle angle is less than the neutral ankle angle. This means that the prosthetic ankle device 100 is relatively more dorsiflexed compared to when operating using the neutral ankle angle. In some embodiments, when the gait speed is at or above the second threshold speed, the speed adaptive ankle angle is greater or more than the neutral ankle angle so that the prosthetic ankle device 100 is relatively more plantarflexed than when operating using the neutral ankle angle. In some embodiments, the controller 305 can be considered to operate the prosthetic ankle device 100 using a speed adaptive ankle angle that is equal to the neutral ankle angle when the user's gait speed is below the first threshold.

FIG. 7 illustrates a graph of the difference or additional angle between the speed adaptive ankle angle and the neutral ankle angle at various gait speeds according to one embodiment. In the illustrated embodiment, the first threshold speed is 0.55 m/s. The first threshold can be set at 0.55 m/s because below that speed, the user may be considered to be standing still or not moving sufficiently or significantly enough to benefit from a change in the ankle angle. Below this speed, the difference between the speed adaptive ankle angle and the neutral ankle angle is 0°, so the prosthetic ankle device 100 operates using the neutral ankle angle. In some embodiments, the “operating” of the prosthetic ankle device using the neutral ankle angle below the first threshold means that the prosthetic ankle device is simply being worn by a user, and the controller need not be doing anything. At 0.55 m/s, the difference between the speed adaptive ankle angle and the neutral angle is about −1°, so the speed adaptive ankle angle is about 1° less than the neutral ankle angle and the prosthetic ankle device 100 becomes about 1° more dorsiflexed compared to the neutral ankle angle. At the first threshold speed, the ankle angle can substantially instantaneously move to the 1° relatively more dorsiflexed position. Alternatively, the ankle angle can gradually transition to the relatively more dorsiflexed position over a period of time or over a range of gait speeds.

In some embodiments, the difference between the speed adaptive ankle angle and the neutral ankle angle decreases as gait speed increases from the first threshold speed to the second threshold speed. The prosthetic ankle device 100 remains relatively more dorsiflexed than the neutral ankle angle below the second threshold speed, but to a lessening extent as the speed adaptive ankle angle increases as gait speed increases. In the illustrated embodiment, the speed adaptive ankle angle increases linearly as gait speed increases. In the graph of FIG. 7, the second threshold speed is about 1 m/s. At or above the second threshold speed, the difference between the speed adaptive ankle angle and the neutral ankle angle is positive, and the speed adaptive ankle angle is greater than the neutral ankle angle. Therefore, when the user's gait speed reaches the second threshold, the prosthetic ankle device 100 passes through the neutral ankle angle and becomes relatively more plantarflexed compared to the neutral ankle angle. The second threshold can be set at a speed considered or determined to be a transition point between slow and fast walking.

In some embodiments, the difference between the speed adaptive ankle angle and the neutral ankle angle increases as gait speed increases above the second threshold. In the illustrated embodiment, the speed adaptive ankle angle increases linearly as the gait speed increases. The prosthetic ankle device 100 therefore becomes relatively more plantarflexed to a greater degree. In some embodiments, the speed adaptive ankle remains constant when the gait speed reaches a third threshold. In the illustrated embodiment, the third threshold speed is about 2 m/s, and at or above the third threshold speed, the speed adaptive ankle angle remains constant at about 2° greater, i.e., more plantarflexed, than the neutral ankle angle.

The graph of FIG. 7 and the threshold speeds therein are provided as examples only, and other threshold speeds and graph shapes are also possible. For example, in some embodiments, the first threshold speed is 0.65 m/s when the prosthetic ankle device 100 is operatively connected to and used by a transtibial amputee and 0.55 m/s when the prosthetic ankle device 100 is operatively connected to and used by a transfemoral amputee, possibly in combination with a prosthetic knee. It can be beneficial to have a lower first threshold speed for transfemoral amputees because a transfemoral user may have a slower gait speed and more limited movement than a transtibial amputee who still has his or her natural knee. In some embodiments, the threshold speeds are determined experimentally for individual users. In some embodiments, the threshold speeds are set and the user's gait speed is determined in terms of stance phase duration, gait cadence, or the like. In some such embodiments, stance phase duration and/or gait cadence can be less affected by variations in stride lengths among different users than a gait speed measured in, for example, meters/second.

In some embodiments, the prosthetic ankle device 100 maintains or is locked at the speed adaptive ankle angle during part or all of the gait cycle. In some embodiments, the prosthetic ankle device 100 adjusts for or allows for adjustment or movement during certain phases of the gait cycle or certain gait patterns or events as described herein at various gait speeds, but such adjustments are made from, using, or relative to the speed adaptive ankle angle rather than the neutral ankle angle. For example, FIG. 8 illustrates a graph depicting a possible range of motion of an embodiment of the prosthetic ankle device 100 used by a transfemoral amputee during one full stride on a level surface at a gait speed of about 0.55 m/s. FIG. 9 illustrates a graph depicting a possible range of motion of an embodiment of the prosthetic ankle device 100 during one full stride on a level surface at a gait speed of about 2 m/s. For FIG. 8, the speed adaptive ankle angle shifts the entire graph of FIG. 6 by 1° toward dorsiflexion, such that the ankle angle of the prosthetic ankle will adjusted according to the curve of FIG. 8 instead of the curve of FIG. 6 at about 0.55 m/s. Similarly, For FIG. 9, the speed adaptive ankle angle shifts the entire graph of FIG. 6 by 2° toward plantarflexion, such that the ankle angle of the prosthetic ankle will adjusted according to the curve of FIG. 9 instead of the curve of FIG. 6 at about 2 m/s. Thus, whereas in FIG. 6 a prosthetic ankle device 100 is configured to adjust to about 10° of dorsiflexion (−10° from the neutral ankle angle) during the swing phase of the gait cycle to provide for toe clearance, the prosthetic ankle device 100 can provide for about 11° of dorsiflexion (−11° from the neutral ankle angle) at a gait speed of about 0.55 m/s and about 8° of dorsiflexion (−8° from the neutral ankle angle) at a gait speed of about 2 m/s.

In some embodiments, the prosthetic ankle device 100 is configured to adapt to the user being in a standing or stopped position or to certain movements the user may make when in a standing or stopped position. For example, the user may shift his or her weight more to his or her sound leg when standing still. If the user does so, the prosthetic ankle device 100 can be configured to cause or allow a slightly dorsiflexed movement to produce a more natural stance and allow the user to more naturally bend his or her knee. This weight-shifting dorsiflexion feature can be triggered by one or more sensors detecting no movement for a period of time, for example about 10 seconds to about 30 seconds. In some embodiments, the weight-shifting dorsiflexion feature can be triggered by the control system 300 detecting or determining vertical lift of and/or reduced load on the prosthetic ankle device 100 with no forward motion. Sensors on the user's sound leg can also be used to detect or determine increased weight or load with no motion. Once this position is detected, in one embodiment an actuator may be used to actively cause the dorsiflexion movement. In some embodiments, the prosthetic ankle device 100 can be triggered to return to normal operation and/or exit a state of weight-shifting dorsiflexion by the control system 300 detecting or determining a slight vertical lowering of and/or an increased load on the prosthetic ankle device 100, possibly accompanied by acceleration. Sensors on the user's sound leg can also be used to detect or determine decreased weight or load and/or motion.

In some embodiments, the prosthetic ankle device 100 is configured to adapt to other movements the user may make when in a standing or stopped position. For example, the user may shift his or her weight to his or her sound leg and extend the leg including the prosthetic ankle device 100. If the user does so, the prosthetic ankle device 100 can be configured to cause or allow plantarflexion to produce a more natural stance and/or appearance. In some embodiments, the control system 300 determines whether to trigger or allow weight-shifting dorsiflexion or weight-shifting plantarflexion using data from one or more sensors configured to measure one or more variables indicative of the angle of the knee, natural or prosthetic, of the leg including the prosthetic ankle device 100. For example, if the knee angle is less than a threshold angle (meaning the knee is more bent or farther away from complete extension), weight-shifting dorsiflexion is triggered. If the knee angle is equal or greater to the threshold angle (less bent or closer to and up to complete extension), weight-shifting plantarflexion is triggered.

Although this disclosure has been described in the context of certain embodiments and examples, it will be understood by those skilled in the art that the disclosure extends beyond the specifically disclosed embodiments to other alternative embodiments and/or uses and obvious modifications and equivalents thereof. In addition, while several variations of the embodiments of the disclosure have been shown and described in detail, other modifications, which are within the scope of this disclosure, will be readily apparent to those of skill in the art. It is also contemplated that various combinations or sub-combinations of the specific features and aspects of the embodiments may be made and still fall within the scope of the disclosure. It should be understood that various features and aspects of the disclosed embodiments can be combined with, or substituted for, one another in order to form varying modes of the embodiments of the disclosure. Thus, it is intended that the scope of the disclosure herein should not be limited by the particular embodiments described above. 

1-19. (canceled)
 20. A method of controlling a prosthetic ankle device comprising a foot unit and a lower limb member, the lower limb member configured to move relative to the foot unit, and the foot unit and the lower limb member defining an angle therebetween, the method comprising: determining that a user of the prosthetic ankle device is in a standing or stopped position and has shifted a majority of body weight to a sound leg; and causing or allowing the prosthetic ankle device to dorsiflex or plantarflex to allow for a more natural stance.
 21. The method of claim 20, wherein determining that the user is in a standing or stopped position and has shifted a majority of body weight to the sound leg comprises detecting or determining vertical lift of, and/or a reduced load on, the prosthetic ankle device with substantially no forward movement of the user for a predetermined period of time.
 22. The method of claim 21, wherein the predetermined period of time is at least about ten seconds.
 23. The method of claim 20, further comprising: determining a vertical lowering of, and/or an increased load on, the prosthetic ankle device; and exiting a state of weight-shifting dorsiflexion.
 24. The method of claim 23, further comprising detecting acceleration of the prosthetic ankle device.
 25. The method of claim 23, further comprising returning to normal operation of the prosthetic ankle device.
 26. The method of claim 20, wherein determining that the user is in a standing or stopped position and has shifted a majority of body weight to the sound leg comprises detecting or determining an increased load on the sound leg with substantially no forward movement of the user for a predetermined period of time.
 27. The method of claim 20, further comprising: determining a knee angle of a knee of a leg that includes the prosthetic ankle device; determining that the knee angle is less than a threshold angle; and causing or allowing the prosthetic ankle device to dorsiflex.
 28. The method of claim 20, further comprising: determining a knee angle of a knee of a leg that includes the prosthetic ankle device; determining that the knee angle is greater than a threshold angle; and causing or allowing the prosthetic ankle device to plantarflex.
 29. A prosthetic system, comprising: a prosthetic ankle device comprising a foot unit and a lower limb member, the lower limb member configured to move relative to the foot unit, and the foot unit and the lower limb member defining an angle therebetween; and a controller configured to: determine that a user of the prosthetic ankle device is in a standing or stopped position and has shifted a majority of body weight to a sound leg; and cause or allow the prosthetic ankle device to dorsiflex or plantarflex to allow for a more natural stance.
 30. The prosthetic system of claim 29, wherein the controller is configured to determine that the user is in a standing or stopped position and has shifted a majority of body weight to the sound leg by detecting or determining vertical lift of, and/or a reduced load on, the prosthetic ankle device with substantially no forward movement of the user for a predetermined period of time.
 31. The prosthetic system of claim 29, wherein the controller is further configured to: determine a vertical lowering of, and/or an increased load on, the prosthetic ankle device; and exit a state of weight-shifting dorsiflexion.
 32. The prosthetic system of claim 31, wherein the controller is further configured to detect acceleration of the prosthetic ankle device.
 33. The prosthetic system of claim 31, wherein the controller is further configured to return the prosthetic ankle device to normal operation.
 34. The prosthetic system of claim 29, wherein the controller is configured to determine that the user is in a standing or stopped position and has shifted a majority of body weight to the sound leg by detecting or determining an increased load on the sound leg with substantially no forward movement of the user for a predetermined period of time.
 35. The prosthetic system of claim 29, further comprising at least one sensor configured to measure one or more variables indicative of a knee angle of a knee of a leg that includes the prosthetic ankle device.
 36. The prosthetic system of claim 29, wherein the controller is configured to: determine a knee angle of a knee of a leg that includes the prosthetic ankle device; determine that the knee angle is less than a threshold angle; and cause or allow the prosthetic ankle device to dorsiflex.
 37. The prosthetic system of claim 29, wherein the controller is configured to: determine a knee angle of a knee of a leg that includes the prosthetic ankle device; determine that the knee angle is greater than a threshold angle; and cause or allow the prosthetic ankle device to plantarflex.
 38. The prosthetic system of claim 36, wherein the knee is a prosthetic knee.
 39. The prosthetic system of claim 37, wherein the knee is a prosthetic knee. 